The recent revolution in technologies virtualizing hardware resources, software, and information storage across networks has increased the reliability, scalability, and cost efficiency of computing. More specifically, the ability to provide on demand virtual computing resources and storage through the advent of virtualization has enabled consumers of processing resources and storage to flexibly structure their computing and storage costs in response to immediately perceived computing and storage needs. Virtualization allows customers to purchase processor cycles and storage at the time of demand, rather than buying or leasing fixed hardware in provisioning cycles that are dictated by the delays and costs of manufacturing and deployment of hardware. Rather than depending on the accuracy of predictions of future demand to determine the availability of computing and storage, users are able to purchase the use of computing and storage resources on a relatively instantaneous as-needed basis.
Virtualized computing environments may provide various guarantees as to the availability and durability of computing resources. Distributing computing resources amongst multiple resource hosts may provide different availability and durability characteristics. For example, virtual computing resources may provide processing resources in the form of compute instances, for example virtual machine instances. As another example, virtual computing resources may provide storage in the form of block-based storage. Such block-based storage provides a storage system that is able to interact with various computing virtualizations through a series of standardized storage calls that render the block-based storage functionally agnostic to the structural and functional details of the volumes that it supports and the operating systems executing on the virtualizations to which it provides storage availability. The compute instance that is logically coupled to (e.g., attached to) one or more volumes of block-based storage doesn't know or care where the physical compute resources that provide the block-based storage are located, and this physical decoupling may provide flexibility for the compute instances.